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The mother of the gunman who killed 12 people and injured eight others at the Washington Navy Yard said at her Brooklyn home Wednesday that she was heartbroken and doesn't know why he did what he did. Brynn Gingras has the story. (Published Wednesday, Sept. 18, 2013)

The mother of the gunman who killed 12 people and injured eight others at the Washington Navy Yard said at her Brooklyn home Wednesday that she was heartbroken and doesn't know why he did what he did.

Cathleen Alexis read a short statement saying her son's actions "have had a profound and everlasting affect on the families of the victims."

Navy Yard Gunman's Mother Speaks

Cathleen Alexis, the mother of the gunman who killed 12 people and injured eight others at the Washington Navy Yard read a short statement at her Brooklyn home Wednesday saying that she was heartbroken and doesn't know why her son did what he did. She added that her son's actions "have had a profound and everlasting affect on the families of the victims." (Published Wednesday, Sept. 18, 2013)

"I don't know why he did what he did and I'll never be able to ask him why," she said. "Aaron is now in a place where he can no longer do harm to anyone, and for that I am glad."

Alexis said she was "so, so very sorry that this has happened."

Gunman's Family in NYC: "Shocked"

The gunman in the mass shooting that left at least 12 dead and more injured at the Washington Navy Yard Monday was born in Queens, lived in the borough decades later and has close family living in Brooklyn. Andrew Siff reports. (Published Tuesday, Sept. 17, 2013)

"My heart is broken," she added.

Her 34-year-old son, who was shot dead by law enforcement after he burst into the Navy Yard complex and began picking off victims, was born in Queens and enlisted in the Navy in New York City in 2007, according to records.

His mother, his 32-year-old sister and his brother-in-law now live in Bedford-Stuyvesant, the brother-in-law said. Another sister, in her late 20s, lives elsewhere.

Alexis was working in IT for a defense-related computer company, and had access to the building through that arrangement.

Two days after the shooting, Alexis' motive remains a mystery. U.S. law enforcement officials told The Associated Press that investigators had found no manifesto or other writings suggesting a political or religious motivation.

There were indications that he may have had emotional or mental issues. A Rhode Island police report from last month said he told police he could hear people talking to him through the walls, floor and ceiling of his motel rooms, and believed people were keeping him awake by sending vibrations into his body.

After the shooting Monday, information emerged that he had previously told family and friends about being traumatized by 9/11. On Tuesday, a spokesman for the Borough of Manhattan Community College, six blocks from ground zero, confirmed that he had worked there as a clerical assistant from February 2001 to February 2003.

It was not clear if he was at work on 9/11, but the spokesman said it was possible.

Alexis' father had told police in Seattle after an arrest there in 2004 that his son was traumatized by 9/11, and claimed he had helped in rescue attempts.

Investigators said there's no evidence Alexis participated in 9/11 rescue operations, law enforcement officials told NBC 4 New York on Tuesday.

A woman who knew him in Fort Worth, Texas, told NBC News Tuesday that he had mentioned seeing the buildings collapse that day and was upset about it.

Alexis lived in Flushing, Queens from at least 2000 to 2002, where he was last registered to vote, according to public records. In October 2000, Alexis applied for a shotgun permit, listing his address as 77th Road in Flushing.

The permit was canceled in 2003 because he failed to renew the permit. It's not clear whether Alexis actually bought a weapon.